Low-salt diet confers similar BP benefit to common first-line antihypertensive medication
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Key takeaways:
- A 7 mm Hg or greater reduction in systolic BP was observed after switching to a low-salt diet.
- The benefit was similar to that of hydrochlorothiazide and was reported in three-quarters of participants.
PHILADELPHIA — Switching to a low-sodium diet conferred BP benefits similar to that of hydrochlorothiazide, a common first-line antihypertensive medication, a speaker reported.
The results of the randomized-order crossover CARDIA-SSBP trial were presented at the American Heart Association Scientific Sessions and simultaneously published in the JAMA.
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“Dietary sodium is a major contributor to blood pressure itself, and on average in the United States, consumption of sodium average is about 3,500 mg per day, which is far in excess of the AHA, World Health Organization and Department of Health and Human Services recommendations of 1,500 mg to 2,300 mg per day,” Deepak K. Gupta, MD, MSCI, FAHA, associate professor of medicine and director of the Vanderbilt Translational and Clinical Cardiovascular Research Center in the division of cardiovascular medicine at Vanderbilt University Medical Center, said during a press conference. “The population impact of excess dietary sodium is profound. It's been estimated to contribute to 1.9 million deaths annually worldwide, based on 2019 data. Projections [are that] reducing from the current 3,500 mg per day down to the recommendation of 2,300 mg per day would reduce deaths in the United States by 44,000 to 92,000 alone, and save somewhere between $12 billion to $20 billion per year."
To assess whether a low-sodium diet could lower BP in patients already taking antihypertensives and/or with diabetes, Gupta and colleagues randomly assigned 213 participants (median age, 61 years; 65% women; 64% Black; 21% with diabetes) to a high-sodium diet with an added 2,200 mg sodium per day or a low-sodium diet on 500 mg sodium per day. After a 7-day waiting period following randomization, each participant followed one diet for 7 days and then crossed over to the other for 7 days.
The high-sodium groups received sodium supplements in the form of bouillon packets. The low-sodium diet was standardized and created in metabolic kitchens at Northwestern University and the University of Alabama at Birmingham and was made available to participants at grocery stores and online retailers.
At baseline, 25% of the cohort had normal BP; 20% had controlled hypertension; 25% had untreated hypertension; and 31% had uncontrolled hypertension.
The primary endpoints were change in 24-hour ambulatory BP, change in urine sodium and proportion with salt-sensitive BP.
The patients’ baseline diets were already high in sodium, at 4,450 mg per day, and median systolic BP was 125 mm Hg.
Participants switched to the high-sodium diet had their average daily sodium intake increased to around 5,000 mg per day, and experienced a small increase in average systolic BP from 125 mm Hg to 126 mm Hg (P = .14).
Average daily sodium after being switched to the low-sodium diet was 1,270 mg per day, and systolic BP was reduced to 119 mm Hg (P < .0001).
At the end of the first diet week, the low-sodium group had a reduction in systolic BP of –8 mm Hg compared with the high-sodium group (95% CI, –4 to –11; P < .0001), Gupta said, noting the results were similar at the end of the second diet week (–7 mm Hg; 95% CI, –3 to –11; P < .0001).
The effect of the low-sodium diet on systolic BP was consistent across subgroups, including age, sex, race, baseline hypertension status and baseline diabetes status.
Gupta reported no significant difference in systolic BP lowering conferred by the low-sodium diet between individuals who were taking antihypertensive medications and those who were not.
Moreover, approximately 75% of participants switched to a low-sodium diet had a systolic BP reduction (median, –7 mm Hg), a reduction similar to that conferred by hydrochlorothiazide, according to the presentation.
“The usual diet for most individuals was already very high in sodium. The decline in blood pressure resulting from dietary sodium reduction was independent of hypertension status. Antihypertensive medication use was consistent across subgroups and did not result in excess adverse events,” Gupta said during the press conference. “We think that clinically meaningful lowering of blood pressure through reduction in dietary sodium was achieved safely and rapidly in one week, in the vast majority of middle-aged elderly individuals with an effect comparable to commonly utilized medications.”
Reference:
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Gupta DK, et al. LBS.04. Using drugs, diet and delivery to optimize hypertension outcomes. Presented at: American Heart Association Scientific Sessions; Nov. 11-13, 2023; Philadelphia.
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